Memory module and memory system

ABSTRACT

In a memory module including a plurality of DRAM chips which transmit/receive a system data signal with a predetermined data width and at a transfer rate and which transmit/receive an internal data signal having a larger data width and a lower transfer rate as compared with the system data signal, the transfer rate of the system data signal is restricted. Current consumption in DRAMs constituting the memory module is large, hindering speed increases. For this memory module, a plurality of DRAM chips are stacked on an IO chip. Each DRAM chip is connected to the IO chip by a through electrode, and includes a constitution for mutually converting the system data signal and the internal data signal in each DRAM chip by the IO chip. Therefore, wiring between the DRAM chips can be shortened, and DLL having a large current consumption may be disposed only on the IO chip.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a memory system including a pluralityof memory modules such as memory sub-systems, particularly to a memorysystem comprising a plurality of memory units in the respective memorymodules.

(2) Description of the Related Art

As this type of memory system, there has heretofore been a DRAM memorysystem comprising a constitution in which a plurality of memory modulesare attached onto a mother board and these memory modules are controlledby a chip set (memory controller) and a plurality of DRAMs are mountedas memory units on the respective memory modules.

For the above-described DRAM memory system, a system has been proposedin which a stub series terminated transceiver logic (SSTL) is used asinterface standards and data can be written/read at a high rate and witha low signal amplitude using a double data rate (DDR) method forinputting/outputting data in synchronization with front and rear edgesof a clock.

As an example of this memory system, a memory system including aplurality of memory modules (i.e., DRAM modules) on which a plurality ofDRAMs are mounted and which are attached to a mother board has beendescribed in Japanese Patent Application Laid-Open No. 2001-256772(hereinafter referred to as Patent Document 1). Specifically, the memorymodule comprises a memory module substrate having a rectangular shape, aplurality of DRAMs arranged in a row in a longitudinal direction of thememory module substrate, a command/address buffer between the DRAMs, anda PLL chip which distributes clocks to the respective DRAMs, and therespective memory modules constitute a memory sub-system.

Here, each DRAM on the memory module extends in a short direction of themodule substrate and is connected to a module data wiring, and thecommand/address buffer and a PLL chip are connected to a modulecommand/address wiring and a module clock wiring extending in the shortdirection of the module substrate.

Furthermore, a module command/address distribution wiring and a moduleclock distribution wiring are drawn out in the longitudinal direction ofthe module substrate in order to distribute commands, addresses, andclocks to the respective DRAMs from the command/address buffer and PLLchip.

In this constitution, a data signal is directly transmitted to a DRAMchip on the memory module constituting each memory sub-system from thememory controller disposed on the mother board substrate, and acommand/address signal and a clock signal are transmitted to the DRAMchip on each memory module via the command/address buffer and PLL chipfrom the memory controller.

According to this memory module constitution, even when a write and readrate with respect to the DRAM chip is lowered as compared with atransfer rate of the system data signal, the system data signal can betransferred to an external circuit at a high rate.

However, as described in Patent Document 1, it has become clear that aconstitution in which a plurality of DRAM chips are arranged in a planeon a mounting substrate cannot meet a requirement for a high data rateof 12.8 GBps with respect to the memory module of the next generation.

On the other hand, in Japanese Patent Application Laid-Open No. 6-291250(Patent Document 2), a semiconductor integrated circuit has beendescribed including a constitution whose length and breadth arestandardized and in which a plurality of IC chips comprising signal padsare stacked on standardized/unified positions and in which the pad ofthe IC chip is connected to another pad by a longitudinal wiring.

In Patent Document 2, as a concrete example, an example is described inwhich four layers of SRAMs are stacked on an address decoder layer (FIG.8 and paragraph 0025). In this case, the address decoder layer isdisposed as a first layer, and SRAM layers are disposed as second tofifth layers. Chip enable buses for individually selecting SRAMs areconnected to the SRAMs disposed in the second to fifth layers.Accordingly, the respective SRMs are individual selected and activated.

In Patent Document 2, one of a plurality of SRAM layers is selected onthe address decoder layer, and the data signal from the selected SRAMlayer is output as it is to the outside from the address decoder layer.

Furthermore, in Japanese Patent Publication No. 9-504654 (PatentDocument 3), a memory package has been described in which a single ICchip is replaced with an IC chip laminate, an interface circuit fortranslating a signal between a host system and the IC chip laminate isincluded in the IC chip laminate (claim 2). Even in this example, thestacked IC chip laminates are selectively controlled by an interfacecircuit so that the laminates operate independently of one another. Inthis case, a signal and transfer rate of the data signal between thehost system and IC chip laminate are equal to those of an internal datasignal inside the IC chip laminate.

In other words, in Cited Document 3, anything is not consideredconcerning a case where an internal data width inside the IC chiplaminate is larger than a data signal width outside the IC chiplaminate.

Moreover, a memory having a three-dimensional structure has beendescribed in U.S. Pat. No. 6,133,640 (Patent Document 4). In PatentDocument 4, a constitution is described in which memory circuits and acontrol logic circuit are individual arranged on a plurality ofphysically separated layers, the memory circuits of the respectivelayers are individually optimized by the single control logic circuit,accordingly the plurality of memory circuits are operated, and cost isreduced.

Among Patent Documents 1 to 4 described above, in Patent Documents 2 to4, anything is not suggested with respect to the memory system and DRAMmodule (memory module) described in Patent Document 1. Furthermore,concerning the memory system in which the width and transfer speed ofthe data signal inside the module are different from those of the datasignal outside the module and problems in the memory system, anything isnot pointed out in Patent Documents 1 to 4 described above.

In the memory system described in Patent Document 1, data from theplurality of DRAMs are transmitted/received as memory sub-system data,and the plurality of DRAMs are arranged in a row in a plane on themodule substrate.

However, it has become clear that with an increase of the number ofDRAMs mounted on the module substrate in this memory sub-system, ademand for a higher speed, especially a demand for a high data rate of12.8 GBps in the memory module of the next generation cannot be met.

As a result of intensive research of a cause for hindering thespeeding-up in the above-described DRAM module by the present inventors,it has become that a wiring topology of a data signal, address commandsignal, and clock signal between the memory controller and each DRAMchip differs by several cm on the mounting substrate with thearrangement of a plurality of DRAM chips in a plane on the mountingsubstrate. Therefore, a difference is made in a signal reach time bythis degree of difference of the wiring topology, that is, skew occurs,and it has become clear that this skew cannot be corrected even usingPLL with an increase of the transfer rate.

Furthermore, there is a problem that when the transfer rate is raised, aconsumption current in the memory sub-system accordingly increases. ADLL circuit for receiving/transmitting a high-frequency transmissionsignal is mounted on each DRAM chip on the memory module, theconsumption current occupies about 15% of a read/write current at 800Mbps, and this results in a circumstance in which an increase ofconsumption current cannot be avoided.

The above-described problem will be concretely described hereinafterwith reference to FIG. 40.

The memory sub-system, that is, the memory module which is an object ofthe present invention will be schematically described with reference toFIG. 40. First, a memory module shown in FIG. 40 comprises a modulesubstrate 200, a plurality of DRAM chips (nine chips) 201 arranged in arow in a plane on the module substrate 200, and a register 202, PLL 203,and serial presence detector (SPD) 204 arranged in a middle portion ofthe module substrate 200, and the module substrate 200 is attached ontoa mother board (not shown) via a connector (not shown).

Here, in addition to the shown memory module, another memory module ismounted together with a chip set (memory controller) on the motherboard, and these plurality of memory modules and the chip set constitutea memory system.

A module data wiring is laid below the respective DRAMs 201 in thedrawing, that is, in a short direction of the module substrate 200. Onthe other hand, a module command/address wiring is disposed below theregister 202 in the drawing. Furthermore, a module clock wiring extendsbelow the PLL 203 in the drawing, and these module command/addresswiring and module clock wiring are connected to a connector disposed ina longitudinal direction of the module substrate 200. The SPD 204 is amemory which determines an operation condition of the DRAM chip 201mounted on the module substrate 200, and usually comprises ROM.

Furthermore, a module command/address distribution wiring is disposedfor each DRAM chip 201 in the longitudinal direction of the modulesubstrate 200, that is, in a transverse direction from the shownregister 202, and a module clock distribution wiring is similarlydisposed for each DRAM chip 201 from the PLL 203.

In the memory module including this constitution, data having a bitnumber in accordance with a bus width of a memory access data bus can beinput/output as module data. However, in this constitution, a topologyof a module data wiring is different from a topology of a module commanddistribution wiring from a module command wiring and topologies of themodule clock wiring and module clock distribution wiring from the PLL203.

On the other hand, in the shown memory module constitution, a method inwhich a broad bus width is used as means for realizing a data raterequired by a processor (general data processing system using SDRAM suchas DDR) and a method in which the transfer rate is raised with a smallbus width (system of RDRAM) are used.

In these methods, for a conventional general memory module constitutedwith a large bus width, 4 to 16 single DRAMs having an IO number of 16,8, 4 are mounted in a row in a plane on the module substrate toconstitute 64 or 72 data buses.

On the other hand, the module command/address signal and module clocksignal are usually shared by all the DRAM chips 201 on the modulesubstrate 200. Therefore, for these wirings, as shown, the register 202and PLL 203 are mounted on the module substrate 200, these register 202and PLL 203 adjust timings for buffering and wiring delay on the module,and the module command/address signal and the module clock signal aresupplied to each DRAM chip 201.

As described above, the data signal, address command signal, and clocksignal distributed from the memory controller (chip set) have physicallydifferent wiring topologies, and transmission characteristics of thesignal differ.

The difference of the signal reach time or the skew which cannot becorrected by the PLL 203 are generated by the difference of thisphysical wiring topology in the data signal, module clock signal, andcommand/address signal, and a problem occurs that this is a largeobstacle in further raising the transfer rate.

Furthermore, as another problem in this type of memory system, there isa problem of a branch wiring on a data wiring caused because it ispossible to additionally dispose the memory module. Usually, the moduleis increased by insertion/detachment with respect to a socket connectedto the bus wiring. Therefore, the data signal is branched on the buswiring and supplied to the DRAM chip 201 in the module. A problem occursthat an obstacle is brought in high-rate signal transmission by signalreflection caused by this branch wiring.

Moreover, when the memory module is increased, deterioration of a signalquality by the branch wiring or that of a signal quality by LC which isparasitic on a DRAM package increases. Therefore, the number ofadditional modules in DDRII using this constitution has a limitation oftwo slots in the actual circumstances. In actual, the data rate whichcan be realized in the memory sub-system by the DDRII using thisconstitution is 533 Mbps per data pin and about 4.26 GBps per systemchannel.

On the other hand, a method has also been proposed in which the transferrate is raised with a small bus width in the memory module of a shownform (RDRAM). In this method, the single RDRAM having an IO number of 16is connected in series on the bus wiring and disposed. Therefore, thedata signal, module address/command signal, and module clock signaldistributed from the memory controller have the physically same wiringtopology, and the difference of the signal reach time in each RDRAM,that is, skew is not generated.

Moreover, since each RDRAM is mounted on the bus, the signal wiring isnot branched.

Therefore, at present, the transfer rate of the bus which can berealized in the memory sub-system by the RD RAM using this constitutionis 1.066 Gbps per data pin. However, since the data width is only twobytes, the data rate of the system is about 2.13 GBps. Furthermore, amethod of constituting the system of two channels is used in order toraise the data rate of the memory system, but the rate is about 4.26GBps even in this case.

In this constitution of the RDRAM, the bus is not branched, but 4 timesor more RDRAMs need to be connected to the same bus in order to realizea required memory capacity. When a large number of RDRAMs are connectedto a long bus in this manner, the deterioration of the signal quality bythe LC parasitic on the RDRAM package increases. Therefore, arestriction is generated on addition of the memory capacity, and it isdifficult to realize the memory capacity required for the system. It isdifficult to realize a high required data rate in a state in which alarge number of DRAMs as loads are connected and held onto a long bus.

Moreover, it is also considered that the IO number in the RDRAM isincreased, but the RDRAM chips and packages increase, and the cost ofthe single RDRAM increases. When the IO number is increased in the sameRDRAM, an accessible page size is reduced by an IO unit, and therequirement of the system is not satisfied.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a memory system capableof solving various problems in a memory module and operating at a highrate.

An object of the present invention is to provide a DRAM memory module inwhich a high-rate operation is possible and current consumption can bereduced.

An object of the present invention is to provide a memory module and amemory system capable of dealing with even a data rate of 12.8 GBpsrequired for a memory system of the next generation.

In the present invention, a memory module can be realized in which adata rate (12.8 GBps) required for a memory system of the nextgeneration is maintained with a sufficiently memory capacity (expansionproperty) and an increase of a current consumption is suppressed.

Specifically, according to a first mode of the present invention, thereis obtained a memory module comprising: a system input/output terminalvia which a system data signal having a predetermined data width isinput/output; and a plurality of memory chips which transmit/receive aninternal data signal broader than the system input/output terminal, thememory module further comprising: an IO chip including a function ofperforming conversion between the system data signal and the internaldata signal in the system input/output terminal, the plurality of memorychips being stacked on the IO chip and being connected to the IO chipvia through electrodes extending through the plurality of stacked memorychips.

In this case, the module further comprises an interposer substrate formounting the IO chip, and the interposer substrate has a terminal formounting, constituting the system input/output terminal.

According to a second mode of the present invention, there is obtained amemory system including a plurality of memory modules which input/outputthe system data signal having the predetermined data width and whichtransmit/receive the internal data signal broader than the system datasignal, wherein each of the plurality of memory modules comprises aconstitution in which an IO chip, and a plurality of memory chipsstacked on the IO chip are stacked.

In this case, the plurality of memory modules may also be attached ontoa common mother board in a plane, or the plurality of memory modules aremounted on a common mounting substrate and may also have a constitutionin which the mounting substrate is attached onto the mother board.

According to a third mode of the present invention, there is obtained asystem comprising: a plurality of memory chips which transmit/receive asystem data signal at a predetermined transfer rate and whichtransmit/receive an internal data signal at an internal processing ratelower than the transfer rate, the system further comprising: an IO chipcomprising a terminal which transmits/receives a data signal at thepredetermined transfer rate and which performs conversion between theinternal data signal at the internal processing rate and the system datasignal at the transfer rate, the plurality of memory chips being stackedon the IO chip.

According to another mode of the present invention, there is obtained aDRAM memory module comprising: an IO chip; a plurality of DRAMs stackedon the IO chip; and an interposer substrate having BGA terminals of allsystem data signals, system address signals, system control signals, andsystem clock signals required to constitute a function of a memorysub-system of a channel, and including a constitution in which aplurality of DRAM chips connected to a pad for input/output and a padfor input of each input/output circuit on the IO chip and stacked on theIO chip are bonded to a data signal terminal, an address signalterminal, and a control signal terminal of the IO chip by the throughelectrodes, a data signal, an address signal, and a control signalbetween the chips are received/transmitted via the through electrodes,and a power supply and GND are supplied to the pads on the IO chip fromthe BGA terminals, and supplied to a power supply of each DRAM and a GNDterminal via the through electrode. In this case, an SPD chip may alsobe stacked on the stacked DRAM chip.

According to another mode of the present invention, there is obtained aDRAM module comprising: an IO chip; a plurality of DRAM chips stacked onthe IO chip; and an interposer substrate having BGA terminals of allsystem data signals, system address signals, system control signals, andsystem clock signals required to constitute a function of a memorysub-system of a channel, wherein each DRAM chip comprises a countercircuit to generate a collation signal with which a control signal or anaddress signal transmitted from the IO chip is collated to receive asignal, and has a constitution in which the DRAM chips having at leasttwo types of different through electrode forming patterns arealternately stacked.

According to another embodiment of the present invention, there isobtained a DRAM module comprising: an IO chip; a plurality of DRAM chipsstacked on the IO chip; and an interposer substrate having BGA terminalsof all system data signals, system address signals, system controlsignals, and system clock signals required to constitute a function of amemory sub-system of a channel, and all the DRAM chips to be stackedhave the same pattern, comprise a plurality of fuse devices, and producecollation signals indicating stacked positions by cut positions of thefuse device.

According to another mode of the present invention, the is obtained aDRAM module comprising: a system input/output terminal via which asystem data signal having a predetermined data width is input/output;and a plurality of memory chips which transmit/receive an internal datasignal broader than the system input/output terminal, the module furthercomprising: an IO chip including a function of performing conversionbetween the system data signal and the internal data signal in thesystem input/output terminal, the plurality of memory chips beingstacked on the IO chip and being connected to the IO chip by throughelectrodes extending through the plurality of stacked memory chips, therespective stacked DRAM chips having a bank constitution and selectivelyoperating by a bank selection signal logically produced from a systembank selection signal by the IO chip.

According to still another mode of the present invention, there isobtained a DRAM module comprising: an interposer substrate comprising aBGA terminal via which a system data signal is input/output; and two IOchips mounted on the interposer substrate, each IO chip being connectedto ½ of system data signal BGA terminals and comprising a constitutionin which BGA terminals other than those of data such as an address,command and clock are shared, a plurality of DRAM chips being stacked onthe two IO chips. In this case, the DRAM chips stacked on the two IOchips constitute two ranks to be simultaneously accessed. In thisconstitution, without increasing a terminal capacity of a data signal, aconstitution freedom degree of a memory capacity is enhanced, a wiringlength on the interposer substrate can be reduced, and characteristicscan accordingly be improved.

Moreover, an SPD chip is preferably mounted on an uppermost stage of oneof the two DRAM chip laminates.

According to still another mode of the present invention, there isobtained a DRAM module comprising: a system input/output terminal viawhich a system data signal having a predetermined data width isinput/output; and a plurality of memory chips which transmit/receive aninternal data signal broader than the system input/output terminal, themodule further comprising: an IO chip having a function of performingconversion between the system data signal and the internal data signalin the system input/output terminal, the plurality of memory chips beingstacked on the IO chip and being connected to the IO chip via throughelectrodes extending through the plurality of stacked memory chips, aplurality of banks controlled by individual array control circuits beingconstituted inside each DRAM chip.

According to further mode of the present invention, there is obtained amemory module comprising: a system input/output terminal via which asystem data signal having a predetermined data width is input/output;and a plurality of memory chips which transmit/receive an internal datasignal broader than the system input/output terminal, the module furthercomprising: an IO chip including a function of performing conversionbetween the system data signal and the internal data signal in thesystem input/output terminal, the plurality of memory chips beingstacked on the IO chip and being connected to the IO chip by throughelectrodes extending through the plurality of stacked memory chips, eachof the stacked DRAM chips comprising a pad for exclusive use in a testand a test circuit connected to the pad for exclusive use in the test.

In this constitution, a test command, test address, and test data signalare supplied from the pad for exclusive use in the test insynchronization with a test trigger signal at a DRAM chip test time, andan address, command, and data signal produced by the test circuit arereceived by a latch signal for a test produced by the test circuit tostart an internal operation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a schematic constitution of a memory moduleaccording to the present invention;

FIG. 2 is an exploded diagram showing the constitution of the memorymodule according to an embodiment of the present invention;

FIG. 3 is a block diagram showing a whole constitution of the memorymodule shown in FIG. 2;

FIG. 4 is a block diagram more concretely showing a partial constitutionof an IO chip 211 shown in FIG. 3;

FIG. 5 is a block diagram showing a concrete constitution of a DRAM chip201 shown in FIG. 3;

FIG. 6 is a block diagram showing a DRAM chip selection circuit for usein the DRAM chip 201 shown in FIG. 5 in more detail;

FIG. 7 is an explanatory view showing an example of the memory moduleaccording to the present invention together with an access method;

FIG. 8 is an explanatory view showing another example of the memorymodule according to the present invention together with the accessmethod;

FIG. 9 is a diagram showing an activated state of the DRAM chip shown inFIGS. 7 and 8;

FIG. 10 is a diagram showing a signal relation shown in FIG. 6;

FIG. 11 is a block diagram showing another constitution example of theDRAM chip selection circuit for use in the DRAM chip 201 shown in FIG.5;

FIG. 12 is a block diagram showing another example of a method ofselecting the DRAM chip according to the present invention:

FIG. 13 is a block diagram concretely showing the constitution of the IOchip shown in FIG. 12;

FIG. 14 is a block diagram showing the concrete constitution of the DRAMchip shown in FIG. 12;

FIG. 15 is a block diagram showing a modification of the DRAM chip shownin FIG. 12;

FIG. 16 is a block diagram showing the schematic constitution of a DRAMmodule according to another embodiment of the present invention and anaccess method;

FIG. 17 is a block diagram showing a modification of the DRAM moduleaccording to another embodiment of the present invention and the accessmethod;

FIG. 18 is an explanatory view showing the constitution of each DRAMchip in the DRAM module according to still another embodiment of thepresent invention;

FIG. 19 is a diagram showing a constitution example of the DRAM moduleshown in FIG. 18;

FIG. 20 is a diagram showing another constitution example of the DRAMmodule shown in FIG. 18;

FIG. 21 is a diagram showing still another constitution example of theDRAM module shown in FIG. 18;

FIG. 22 is a block diagram showing an operation in the DRAM module shownin FIGS. 18 to 21;

FIG. 23 is a block diagram concretely showing the constitution of the IOchip shown in FIG. 22;

FIG. 24 is a block diagram concretely showing the constitution of theDRAM chip shown in FIG. 22;

FIG. 25 is a block diagram showing another constitution example of theIO chip shown in FIG. 22;

FIG. 26 is a diagram showing the schematic constitution of the DRAMmodule according to another embodiment of the present invention;

FIG. 27 is a diagram showing the schematic constitution of the DRAMmodule according to still another embodiment of the present invention;

FIG. 28 is a diagram showing a bank and wiring of the DRAM module shownin FIG. 27;

FIG. 29 is a block diagram showing the constitution of one of DRAMlaminates in the DRAM module shown in FIG. 28;

FIG. 30 is a block diagram showing the constitution of the other DRAMlaminate in the DRAM module shown in FIG. 28;

FIG. 31 is a time chart showing a read operation in the DRAM moduleaccording to the present invention;

FIG. 32 is a time chart showing a case where a continuous read operationis performed in the DRAM module according to the present invention;

FIG. 33 is a time chart showing a write operation in the DRAM moduleaccording to the present invention;

FIG. 34 is a time chart showing the write operation of test data in theDRAM module according to the present invention;

FIG. 35 is a time chart showing a test data read operation in the DRAMmodule according to the present invention;

FIG. 36 is a time chart showing a test data comparison operation in theDRAM module according to the present invention;

FIG. 37 is a circuit diagram showing a data latch circuit for use duringa test;

FIG. 38 is a perspective view showing one example of a memory systemincluding a plurality of DRAM modules according to the presentinvention;

FIG. 39 is a perspective view showing another example of the memorysystem including a plurality of DRAM modules according to the presentinvention; and

FIG. 40 is a plan view showing a conventional DRAM module.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a memory module according to a first embodiment ofthe present invention is shown. The memory module shown in FIG. 1 iscapable of inputting/outputting a data signal corresponding to a datawidth of a plurality of DRAM chips as a memory data bus width in thesame manner as in the memory module shown in FIG. 40. The memory moduleshown in FIG. 40 can be formed in a stacked structure shown in FIG. 1 inthis manner to constitute a memory system including a plurality ofmemory sub-systems in the whole memory system and having a data rate of12.8 GBps in each memory sub-system and capable of increasing a memorycapacity by expansion and reducing a mounting area.

The shown memory module comprises an interposer substrate 210, an IOchip 211 mounted on the interposer substrate 210, and eight DRAM chips201 stacked on the IO chip 211. Here, first to eighth DRAM chips will bereferred to upwards from the DRAM chip of a lowermost layer adjacent tothe IO chip 211. The memory module mentioned herein indicates aconstituting unit of a memory sub-system comprising a plurality of DRAMsingle bodies so as to satisfy a memory capacity required by a chip set(CPU) and the data rate (data bus width (64, 72, 128, 144, 16 forRDRAM)×transfer rate).

Next, parts constituting the memory module will be described. Each DRAMchip 201 has a thickness of about 50 μm, the IO chip 211 is connected tothe respective DRAM chips 201 by through electrodes 215, and a datasignal is transmitted/received with respect to the IO chip 211 via thethrough electrodes 215. Here, the through electrodes 215 are chipconnecting electrodes each extending to the other surface from onesurface of each DRAM chip 201, and it is assumed in this example that72×4 (=288) through electrodes formed of copper or aluminum aredisposed.

Furthermore, the interposer substrate 210 is formed of silicon, has BGAterminals corresponding to on-board mounting pitches of all system datasignals, system address signals, system control signals, and systemclock signals necessary for constituting a function of the memorysub-system of a channel, and includes a function capable of connectingeach signal BGA terminal to each signal pad on the IO chip formed of asilicon chip by a substrate wiring and bump.

Moreover, the IO chip 211 includes pads and interface circuits of allthe system data signals, system address signals, system control signals,and system clock signals necessary for constituting the function of thememory sub-system of the channel. Here, the channel is a unit of data tobe processed by the chip set (CPU), and here, for example, 64 or 72 bitsare assumed.

Roughly speaking, the IO chip 211 includes a function of re-constitutinga signal input from the chip set in order to operate the DRAM chips 201,a function of transmission to the DRAM chips 201 from through electrode215 terminals, a function of receiving the signal from the DRAM chips201 from the through electrode 215 terminal, and a function ofre-constituting the data signal received from the DRAM chip 201 totransmit the system data signal.

The shown memory module comprises the interposer substrate 210 includingthe BGA terminals for all the system data signals, system addresssignals, system control signals, and system clock signals necessary forconstituting the function of the memory sub-system of the channel. TheBGA terminals of the interposer substrate 210 are connected to a pad forinput/output and a pad for input of each input/output circuit on the IOchip 211. Data signal terminals, address signal terminals, and controlsignal terminals of the plurality of DRAM chips 201 stacked on the IOchip 211 and IO chip 211 are bonded by the through electrodes 215, andthe data signal, address signal, and control signal between the chipsare received/transmitted via the through electrode 215. A power supplyand GND are supplied to the pads on the IO chip 211 from the BGAterminals of the interposer substrate 210, and supplied to a powersupply of each DRAM chip 201 and a GND terminal via the throughelectrode 215.

Here, each DRAM chip 201 includes the number, which is 2n (n is anatural number of 1 or more) times that of system data buses, of throughelectrode data signal terminals for write and read, or bidirectionalterminals. On the other hand, the IO chip 211 includes the number, whichis 2n times that of system data buses, of through electrode data signalterminals for write and read, or bidirectional terminals.

Mutual data transfer is performed between the DRAM chips 201 and the IOchip 211 comprising this constitution via data terminals of the throughelectrodes 215.

In this case, the IO chip 211 has a serial/parallel circuit whichserial/parallel converts 2n data signals per continuous terminaltransferred via a system data bus to simultaneously transfer the datasignals to the DRAM chips 201. Furthermore, the IO chip 211 includes aparallel/serial circuit, and parallel/serial converts 2n data perterminal transferred from the DRAM chip 201 to output continuous 2n datato the system data bus.

Furthermore, the IO chip 211 includes an interface with a system databus of 64 mbits or 72 mbits including a parity bit (m is a naturalnumber of 1 or more).

The data signal terminal of each DRAM chip 201 is connected to that ofthe IO chip 211 via the through electrode 215. In this case, the throughelectrode 215 which is a data signal line is shared by the DRAM chips201. The address signal terminals of the respective DRAM chips 201 sharethe through electrode 215 as an address signal line, and are connectedto the address signal terminal of the IO chip 211. Furthermore, thecontrol signal terminals of the respective DRAM chips 201 share thethrough electrode 215 as a control signal line, and are connected to thecontrol signal terminal of the IO chip 211.

It is to be noted that in this example, after re-wiring by a waferpackage process (WPP), the bumps are formed on the IO chip 211.

Furthermore, an SPD may also be disposed in the memory module in thesame manner as in FIG. 40. In this case, the SPD writes information suchas a memory capacity, bank constitution, and assured operation speed ofthe memory module, and the chip set includes a function of referring tothe information to automatically set control conditions at a system boottime. When the SPD chip is disposed on a laminate of the DRAM chips 201,the input/output signal terminal of the SPD chip is connected to an SPDinput/output terminal pad on the IO chip 211 via the through electrode215. Each of the DRAM chips 201 includes the through electrode for SPDinput/output signal, which is not used in the DRAM chip 201.

Here, the DRAM chips 201 constituting the laminate have the same patternin forming a pattern other than a pattern of the through electrode 215.Since the same pattern is formed on all the DRAM chips 201 to be stackedin this manner, a fuse device is separately disposed beforehand, and iscut for each of the DRAM chips 201 so that a signal to each of the DRAMchips 201 from the IO chip 211 can be identified.

The memory module according to a second embodiment of the presentinvention will be described with reference to FIG. 2. Each DRAM chip 201shown in FIG. 2 comprises a counter circuit 300 which produces acollation signal with which a control signal or an address signaltransmitted from the IO chip 211 is collated to receive a signal, and achip identification code production circuit 301 is disposed in the IOchip 211.

Furthermore, as shown in FIG. 2, DRAM chips 201a and 201c comprises thesame through electrode forming pattern 251. On the other hand, a DRAMchip 201b comprise a through electrode forming pattern 252 differentfrom the through electrode forming pattern 251 of the DRAM chips 201aand 201c. The IO chip 211 is connected to the through electrode formingpattern 251 of the DRAM chip 201a by through electrodes 215a, the DRAMchip 201a is connected to 201b by through electrodes 215b, and furtherthe DRAM chip 201b is connected to 201c by the through electrodes 215a.Only two through electrodes are shown for the shown through electrodes215a and 215b, and two or more electrodes may also be disposed. It is tobe noted that the other through electrodes 215 are omitted forsimplification of the drawing.

Specifically, the through electrode forming pattern 251 on the DRAM chip201a inputs from the through electrodes 215a with respect to the counter300 on the DRAM chip 201a, and outputs an output from the counter 300 tothe through electrodes 215b. Furthermore, the through electrode formingpattern 252 of the DRAM chip 201b supplies the output from the DRAM chip201a with respect to the counter 300 on the DRAM chip 201b, and theoutput from the counter 300 of the DRAM chip 201b is output to thethrough electrode forming pattern 251 of the DRAM chip 201c of an upperlayer via the through electrodes 215a. In this constitution, countvalues of the respective DRAM chips 201a, 201b, 201c are successivelyoutput to the DRAM chip of the upper layer.

In this manner, the shown memory module comprises a constitution inwhich the DRAM chips 201 comprising mutually different through electrodeforming patterns 251 and 252 are alternately stacked. According to thisconstitution, signals of a plurality of bits output from the IO chip 211are input into the counter 300 of the DRAM chip 201a of the lowermostlayer, the output of the counter 300 is supplied to the counter 300 ofthe next layer, and incremented signals are successively transmitted tothe DRAM chip of the uppermost layer. In this constitution, differentcounter output values can be obtained in the respective DRAM chips, andaccordingly each DRAM chip 201 is capable of producing the collationsignal using the counter output value inside to identify the controlsignal and address signal with respect to each DRAM chip 201.

The DRAM chips 201 comprising the above-described two types of throughelectrode forming patterns 251 and 252 can be easily manufactured, whenthe input/output of the counter 300 is only replaced by two types ofmask patterns at a through electrode forming time.

Next, FIG. 3 shows a concrete example of the whole memory module shownin FIG. 2. In FIG. 3, as shown in FIG. 2, eight DRAM chips 201 (DRAM-1to DRAM-8) are mounted on the single IO chip 211. FIG. 4 more concretelyshows the constitution of a part of the IO chip 211 shown in FIG. 3,FIG. 5 shows the concrete constitution of the DRAM chip 201 shown inFIG. 3, and further FIG. 6 shows a DRAM chip selection circuit for usein the DRAM chip 201 shown in FIG. 5 in more detail.

Referring to FIG. 3, the IO chip 211 includes an input/output circuit111, input circuit 112, internal control circuit 113, DLL 114, andcounter start value production section 115 for transmitting/receivingvarious signals with respect to the interposer substrate (not shown).Furthermore, the chip comprises a data control circuit, serial/parallelconversion circuit, parallel/serial conversion circuit, address controlcircuit, and bank selection signal production circuit. FIG. 3 shows acombination of the data control circuit, serial/parallel conversioncircuit, and parallel/serial conversion circuit by a reference numeral116, and a combination of the address control circuit and bank selectionsignal production circuit by a reference numeral 117. In FIG. 4, theaddress control circuit and bank selection signal production circuit aredenoted with reference numerals 117a and 117b, respectively.

As shown in FIG. 3, system clock signals CK, /CK, system address signalsAO to Ai, and system bank address signals BA0 to BA2 are suppliedtogether with control signals such as /RAS, /CAS, /WE, /CS, and strobesignal DQS to the IO chip 211 from the chip set (not shown) which is amemory controller. Furthermore, data signals DQ0 to DQ63 and DM0 to DM7are transmitted/received between the chip set and the IO chip 211. Aconventional circuit is usable as the data control circuit and serialparallel/parallel serial conversion circuit 116 shown in FIG. 3. Here,although not described in detail, internal data signals IDQ0 to 255,IDM0 to 31 are transmitted/received between the circuit 116 and eachDRAM chip 201. It is to be noted that in the embodiment of the presentinvention, the DLL 114 is disposed only in the IO chip 211, and is notdisposed in each DRAM chip 201.

System address signals a0 to Ai, and system bank address signals BA0 toBA2 are supplied to the circuit 117 of the IO chip 211 shown in FIG. 3,and the circuit is connected to the counter start value productionsection 115. Furthermore, the counter start value production section 115supplies three-bit count signals S0 to S2 to the counter circuit of theDRAM chip 201 (DRAM-1) of the lowermost layer.

FIG. 4 also concretely shows a part of the IO chip 211 shown in FIG. 3.

FIG. 4 shows the internal control circuit 113, counter start valueproduction section 115, address control circuit 117a, and bank selectionsignal production circuit 117b in the IO chip 211. Among the circuits,the internal control circuit 113 outputs an initialization signal RE.This initialization signal RE usually takes a high level, and isgenerally a pulse signal having a low level at an initialization time ofthe DRAM chip 201 on the module, performed in the system.

In the memory module shown in FIG. 3, four DRAM chips 201 may also bestacked on the single IO chip 211 as shown in FIG. 7, and eight DRAMchips 201 may also be stacked on the single IO chip 211 as shown in FIG.8. In either FIG. 7 or 8, as shown by slanted lines, only one DRAM chipis selected from the td DRAM chips 201. In this manner, for the memorymodule according to the present invention, the number of DRAM chips 201stacked on the IO chip 211 can be changed, and therefore the IO chip 211needs to be capable of judging the number of stacked DRAM chips 201.

In the example shown in FIGS. 7 and 8, the respective DRAM chips 201constitute a single bank, and further each DRAM chip 201 comprises ×256data terminals. On the other hand, the IO chip 211 comprises ×64 systemdata lines. Therefore, the data terminals of the DRAM chip and thesystem data lines of the IO chip 211 have a relation of 4:1. Therefore,in this constitution, an output operation frequency of the DRAM chip 201is reduced to ¼, and a test in a wafer state is also easy. Oneread/write access with respect to the memory module is performed withrespect to one DRAM chip 201.

Referring to FIG. 9, a bank constitution of each DRAM chip 201 shown inFIGS. 7 and 8 is shown. The DRAM chip 201 shown in FIG. 9 comprises acapacity of 512 Mbit, and includes a single bank constitution in thesame manner as in the existing 512 Mbit DDRII DRAM. The shown DRAM chip201 is divided into four 128 Mbit cell arrays, and an interconnectionarea and test pad are disposed in a middle portion. When the address ofthe DRAM chip is designated, two regions are activated in each cellarray region, and it is possible to read or write data signals of 256bits in total, 64 bits from each array. Here, an activated state means astate in which a sense amplifier is operable, and a data unit in thisstate is referred to as a page. As a result, the shown DRAM chip 201 hasa page of 8 kbytes.

An operation of the memory module shown in FIGS. 3 to 6 will bedescribed on the assumption of the constitution shown in FIGS. 7 to 9.As also apparent from FIG. 3, in addition to the system address signalsA0 to Ai, the system bank address signals BA0 to BA2 of the system aresupplied to the address control circuit 117a of the IO chip 211 shown inFIG. 4.

In this state, the address control circuit 117a shown in FIG. 4 judgesthe bank of the target DRAM chip 201 from the bank address signals BA0to BA2, here, a stacked position to output the position to the bankselection signal production circuit 117b.

A laminate number recognition signal is supplied to the bank selectionsignal production circuit 117b via laminate number recognition signallines C8R, C4R.

In this example, as shown in FIG. 8, when eight DRAM chips 201 arestacked, both the laminate number recognition signal lines C8R, C4Rbecome high. As a result, bank selection signals BA0N/T to BA2N/Tproduced from the bank selection signal production circuit 117b of theIO chip 211 are all enabled, and the memory module takes in bank addresssignals BA0, 1, 2 of the system to operate in an eight-bankconstitution.

On the other hand, when four layers of DRAM chips 201 are stacked asshown in FIG. 7, the laminate number recognition signal line C8R is low,C4R is high, the bank selection signals BA0N/T to BA1N/T produced fromthe bank selection signal production circuit 117b of the IO chip 211 areenabled, and BA2N/T is fixed at a high level. As a result, the memorymodule takes in the bank address signals BA0, 1 of the system to operatein a four-bank constitution.

The internal control circuit 113 shown in FIG. 4 produces theinitialization signal RE which usually has a high level and turns to apulse signal having a low level at an initialization time of the DRAMchip 201 on the module. The initialization signal RE initializes thelevels on the laminate number recognition signal lines connected to thelaminate number recognition signal lines (C4R, C8R), respectively. Onthe initialization by the initialization signal RE, the states of thelaminate number recognition signal lines (C4R, C8R) have levels inaccordance with the number of DRAM chips 201 to be stacked as describedabove.

Moreover, the counter start value production section 115 of FIG. 4outputs the count signals S0 to S2 of three bits. In this example, thecount signals S0 to S2 are assumed to be 111. As a result, the countercircuit 300 of the DRAM chip 201 of the lowermost layer increments only1, and outputs 000. Subsequently, the counter circuit 300 of the DRAMchip 201 of each layer similarly increments only 1, and successivelysends out the count value to the upper layer.

As a result, when the DRAM chips 201 are stacked, the laminate numberrecognition signal line C4R becomes high by an output from the fourthDRAM chip 201 from the lower layer. Since the eighth DRAM chip 201 fromthe lower layer is not stacked, the laminate number recognition signalline C8R remains low. When eight layers of DRAM chips 201 are stacked,the laminate number recognition signal line C4R becomes high by theoutput from the fourth DRAM chip 201 from the lower layer, and thelaminate number recognition signal line C8R becomes high by the outputfrom the eighth DRAM chip 201 from the lower layer. Accordingly, thelaminate number of the DRAM chips 201 can be recognized.

Next, the DRAM chip 201 shown in FIG. 5 includes a DRAM chip selectioncircuit block 150 including the counter circuit 300 connected to thecounter start value production section 115 of the IO chip 211. The shownDRAM chip 201 comprises a control circuit 171, address buffer 172, anddata buffer 173 in addition to a memory cell array 170 including acolumn decoder, sense amplifier, data amplifier, and row decoder.

Furthermore, the shown DRAM chip 201 is characterized in that a pad fortest 175 and test circuit 176 are mounted on the DRAM chip 201considering that each DRAM chip 201 cannot be tested in a stackedrelation of the shown DRAM chip 201.

Here, referring also to FIG. 6, the above-described count signals S0 toS2 are supplied as count input signals S0_in to S2_in to the countercircuit 300 of the DRAM chip selection circuit block 150, and the countvalue incremented only by one are sent out as counter outputs S0_out toS2_out to the DRAM chip 201 of the upper layer.

Furthermore, the shown counter circuit 300 produces the collationsignals (S0T/N to S2T/N) in response to the counter outputs S0_out toS2_out, and outputs the signals to an in-DRAM latch signal productioncircuit 151. The in-DRAM latch signal production circuit 151 collatesthe collation signals (S0T/N to S2T/N) applied from the counter circuit300 with the bank selection signals (BA0T/N to BA2T/N) transmitted fromthe bank selection signal production circuit 117b of the IO chip 211 toproduces an in-DRAM latch signal in the DRAM chip in a case ofagreement. It is to be noted that, as shown in FIG. 3, a latch signalLAT is supplied to the shown in-DRAM latch signal production circuit 151from the internal control circuit 113 in the IO chip 211.

The in-DRAM latch signals are applied to the control circuit 171,address buffer 172, and data buffer 173 of FIG. 5, and data signals of256 bits are read from the memory cell array 170, or a writable state isattained with respect to the memory cell array 170.

It is to be noted that when the counter circuit 300 shown in FIG. 6 hasfour-layer and eight-layer structures, position control signals C4 andC8 are output to C4R, C8R via a logic circuit in order to identify theDRAM chip 201 positioned in an uppermost layer.

Each DRAM chip 201 comprising this constitution receives the bankselection signals (BA0T/N to BA2T/N) logically produced by the IO chip211 to selectively operate by the operation of the DRAM chip selectioncircuit block 150.

Furthermore, as shown in FIG. 5, the in-DRAM latch signal is input intothe control circuit 171 in the DRAM chip, the control signal of the DRAMchip 201 is produced in response to the command signal, and input intothe address buffer 172 and data buffer 173, and the data signaltransmitted from the IO chip 211 can be taken into the DRAM chip 201.

Moreover, it is seen that the number of stacked DRAM chips is recognizedby the levels of the laminate number recognition signal lines C4R, C8Rto allocate the logic level of the control signal or the address signalto the respective DRAM chips.

Furthermore, the shown test circuit 176 is connected to the controlcircuit 171, address buffer 172, and data buffer 173, latch signals forthe test are output to these circuit 171 and buffers 172, 173, and atest command signal, test address signal, and test data signal are alsooutput. Accordingly, the stacked DRAM chips 201 can be individuallytested.

Referring to FIG. 10, the values of the count input signals S0_in toS2_in, output signals S0-out to S2_out, collation signal s (S0T/N toS2T/N), and position control signals C4 and C8 in the DRAM chipselection circuit block 150 shown in FIG. 6 are shown in order to theeighth layer from the first layer which is the lowermost layer.

In the DRAM chip 201 shown in FIG. 6, the counter circuit 300 isdisposed in the selection circuit block 150, and the collation signals(S0T/N to S2T/N) in the DRAM chip 201 are produced by this countercircuit 300. In this manner, in the constitution using the countercircuit 300, as described with reference to FIG. 2, the mutuallydifferent through electrode forming patterns 251 and 252 need to beformed in the DRAM chip 201.

A DRAM chip selection circuit block 150a shown in FIG. 11 comprises aconstitution in which all the patterns of the stacked DRAM chips 201 arethe same and the collation signals (S0T/N to S2T/N) can be produced inaccordance with the stacked positions of the stacked DRAM chips 201.Specifically, the shown DRAM chip selection circuit block 150a includesa fuse circuit 180 which receives the initialization signal RE tooperate instead of the counter circuit 300 (FIG. 6). Here, three fusecircuits 180 are disposed considering a case where eight DRAM chips 201are stacked.

As apparent from the drawing, each fuse circuit 180 comprises aconstitution in which a fuse device 181 is disposed between drains of Nchannel MOS and P channel MOS and a pair of inverter circuits aredisposed on one end of the fuse device 181, and outputs of the oppositeends of the pair of inverter circuits are applied to the in-DRAM latchsignal production circuit 151. The fuse device 181 is cut in accordancewith the stacked position of the DRAM chip 201, and the collation signalcan be produced in the same manner as in FIG. 6.

According to this constitution, the pattern of the DRAM chip 201 doesnot have to be changed for each layer, but the DRAM chips 201 of thefuse device 181 having different cut places need to be manufactured inaccordance with the laminate number.

It is to be noted that the shown DRAM chip 201 changes the level of thelaminate number recognition signal line (C4R, C8R) shared by each DRAMchip 201 and the IO chip 211 via the through electrode in response tothe collation signal, and accordingly the DRAM chip of the uppermostlayer can be identified.

Another example of a method of selecting the DRAM chip according to thepresent invention will be described with reference to FIGS. 12 to 14.The memory module shown in FIG. 12 is different from the memory moduleshown in FIG. 3 in that the module comprises the IO chip 211 and eightDRAM chips 201 and that chip select signals CSEL1 to 8 corresponding tothe DRAM chips 201 are output to the DRAM chips 201 from the internalcontrol circuit 113 through eight through electrode terminals.Therefore, the memory module is different from that of FIG. 3 in thatthe system address signals A0 to Ai and system bank address signals BA0to 2 are supplied to the address control circuit 117a and that the bankselection signal production circuit 117b (FIG. 3) is not disposed.

The address control circuit 117a of the IO chip 211 shown in FIG. 13produces an internal bank address signal from the system bank addresssignals BA0 to 2, and outputs the signal to an internal control circuit113a. The internal control circuit 113a produces the chip selectionsignals CSEL1 to 8 from the internal bank address signal in accordancewith the stacked positions of the stacked DRAM chips 201. Any throughelectrode terminal is selected from eight terminals to output the chipselect signals CSEL1 to 8 to the through electrode terminal. Since thecounter start value production section 115 and the laminate numberrecognition signal lines C4R, C8R have been described with reference toFIG. 4, they are not described in detail here.

Referring to FIG. 14, the DRAM chip selection circuit block 150 is shownwhich receives the chip selection signals CSEL1 to 8 and count signalsS0 to S2 output from FIG. 13 to operate. The DRAM selection circuitblock 150 shown in FIG. 14 receives the count signals S0 to S2 as thecount input signals S0_in to S2_in to output the counter output signalsS0_out to S2_out, and the number, corresponding to the laminate numberof DRAM chips 201, of output terminals B1 to B8.

In this example, the counter circuit 300 selects one of output terminalsb1 to 8 in accordance with the counter value to output the signal to thein-DRAM latch signal production circuit 151. In this case, for theoutput terminals B1 to B8, only the terminal corresponding to the layernumber of the DRAM chip 201 indicates the high level, and the otherterminals indicate the low level.

The chip selection signals CSEL1 to 8 any of which takes the high levelare supplied to the shown in-DRAM chip latch signal production circuit151 via the through electrodes. Therefore, the in-DRAM latch signalproduction circuit 151 of the DRAM chip 211 of the stacked position(layer number) outputs the in-DRAM latch signal, and only the signalfrom the selected through electrode is taken into the DRAM chip 201.

Here, an example in which the in-DRAM latch signal is produced by thechip selection signal CSEL and operation is performed in the same manneras in the above-described method, but the method of the present systemmay be means for receiving/transmitting the signals of the IO chip 211and individual DRAM chips 201.

In FIG. 14, the DRAM chip selection circuit block 150 has been describedwhich identifies the stacked position to output the in-DRAM latch signalusing the counter circuit 300, but instead of the counter circuit 300,the fuse circuit 180 may also be disposed in accordance with therespective chip selection signals CSEL1 to 8 in the same manner as inFIG. 11.

Referring to FIG. 15, as a modification of FIG. 14, an example is shownin which fuse circuits 180 are disposed by the number corresponding tothe laminate number of the DRAM chips 201. A shown DRAM chip selectioncircuit block 150b comprises eight fuse circuits 180 connected to aninitialization signal RE terminal, and output terminals of the fusecircuits 180 are connected to NAND gates disposed corresponding to thechip selection signals CSEL1 to 8. Since the constitution of the fusecircuit 180 is similar to that of FIG. 11, the description is omitted,but the fuse device 181 of each fuse circuit 180 can be cut to producethe signals corresponding to B1 to B8.

Referring to FIG. 16, the memory module according to a third embodimentof the present invention is shown. The memory module can have a memorycapacity equal to that of a conventional 2-rank memory module. For theshown memory module, a constitution suitable for a case where two DRAMchips 201 are simultaneously objects of access is shown.

Specifically, for the memory module, two IO chips 211a and 211b mountedon the interposer substrate (not shown), and four layers of DRAM chips201a, 201b on the IO chips 211a, 211b are stacked, and the DRAM chips201a, 201b on the respective IO chips 211a and 211b are simultaneouslyaccessed one by one to constitute a 2-rank memory module. In this case,the data signals of ×256 bits are transmitted/received between thesimultaneously accessed DRAM chips 201a, 201b and IO chips 211a and211b, and the system data signals of ×32 bits are transmitted/receivedbetween the respective IO chips 211a and 211b and the chip set. In thedrawing, a pair of DRAM chips 201a, 201b which are simultaneous accessobjects constitute the same banks 0 to 3.

On the other hand, the system address signal, command, and clock signalare supplied to two IO chips 211a and 211b in common. Furthermore, therespective IO chips 211a and 211b are connected to the half of thesystem data signal BGA terminals on the interposer substrate, and theterminals for the signals other than the data signal use a constitutionshared by both the IO chips 211a and 211b. When the IO chips 211a and211b are connected to the half of the system data signal BGA terminalson the interposer substrate, deterioration of transmissioncharacteristics of signals by an increase of an input capacity can bereduced.

Referring to FIG. 17, as a modification of the memory module shown inFIG. 16, a memory module is shown in which eight DRAM chips 201a, 201bare stacked on two IO chips 211a and 211b, and in this relation, theDRAM chips 201a, 201b of banks 0 to 7 are stacked on the respective IOchips 211a and 211b to the eighth layer which is the uppermost layerfrom the first layer which is the lowermost layer.

Also in this example, two IO chips 211a and 11b are connected to ½ ofsystem data signal BGA terminals on the interposer substrate, and sharethe BGA terminals for the address, command, and clock except the data.

It has been confirmed that when two IO chips 211a and 211b are mountedon the interposer substrate in this manner, a wiring length to the padson the IO chips 211a and 211b from the BGA terminals of the data signalson the interposer substrate can be reduced.

In the example shown in FIGS. 16 and 17, the DRAM chips 201a, 201b have×256 data terminals, there are inputs/outputs with respect to ×32 datalines of the system in the parallel serial conversion circuit of the IOchips 211a and 211b, therefore the data terminals of the DRAM chips201a, 201b and the data line of the system have a constitution of 8:1,and the constitution is capable of dealing with a higher operationfrequency.

In addition to the above-described embodiment, each DRAM chip 201 mayalso be formed in a 2-bank constitution.

Referring to FIG. 18, an example is shown in which a 512 Mbit DRAM chip201 is formed in the 2-bank constitution including 256 Mbit banks A andB. In this 2-bank constitution, only the half of the inside of the DRAMchip 201 is activated, and 256 bit data signals can be read from theactivated bank A. When each DRAM chip 201 is formed in the 2-bankconstitution, an activated page size becomes half as compared with FIG.9, and the page size is 4 kbyte in FIG. 18.

Referring to FIG. 19, the memory module according to a fourth embodimentof the present invention comprises a constitution in which the DRAMchips each having the 2-bank constitution are stacked. The shown examplehas a constitution in which two IO chips 211a and 211b are mounted onthe interposer substrate 210 (not shown) and two DRAM chips 201a, 201bare stacked on two IO chips 211a and 211b. Each of the DRAM chips 201a,201b stacked on the IO chips 211a and 211b has the 2-bank constitutionas shown in FIG. 19.

Among the shown DRAM chips 201a, 201b, banks 0, 2 are allocated to theDRAM chips 201a, 201b in most vicinity of the IO chips 211a and 211b,that is, in the lowermost layer. On the other hand, banks 1, 3 areallocated to the upper-layer DRAM chips 201a, 201b.

Here, the respective IO chips 211a and 211b are connected To ½ of thesystem data signal BGA terminals, and share the BGA terminals for theaddress, command, and clock except the data.

According to this constitution, a constitution freedom degree of thememory capacity can be enhanced without increasing a terminal capacityof the data signal, and characteristics by reduction of the wiringlength on the interposer substrate can be improved.

Referring to FIG. 20, as a modification of the memory module shown inFIG. 19, an example is shown in which four DRAM chips 201a, 201b eachhaving the 2-bank constitution are stacked on two IO chips 211a and211b. In this case, banks (0, 4), (1, 5), (2, 6), (3, 7) are allocatedto four DRAM chips 201a, 201b to the uppermost layer from the lowermostlayer, and ×128 data signals are transmitted/received between therespective banks and the IO chips 211a and 211b. On the other hand, ×32system data signals are transmitted/received between the respective IOchips 211a and 211b and the chip set.

Referring to FIG. 21, another modification of the memory module shown inFIG. 19 is shown. As apparent from the drawing, the module is similar tothose of FIGS. 19 and 20 except that eight DRAM chips 201a, 201b eachhaving the 2-bank constitution are stacked on two IO chips 211a and211b.

As shown in FIGS. 19 to 21, when the respective DRAM chips 201a, 201bare constituted of a plurality of banks, a memory module can be entirelyconstituted to have a bank number equal to a DRAM chip number×(banknumber in DRAM chip). In this case, a page size at a time when theinside of the DRAM chip 201a or 201b is operated as a plurality of banks(n banks) is 1/n. Moreover, it is also possible to select whether or notto operate the inside of the DRAM chip 201a, 201b as a plurality ofbanks (n banks) by the BGA terminal level.

Concrete circuit constitutions of the memory modules shown in FIGS. 19to 21 will be described with reference to FIGS. 22 to 24. Controlsignals MIO, MB for controlling the respective DRAM chips 201a, 201beach having the 2-bank constitution are supplied to each IO chip 211shown in FIG. 22, and the control signals MIO, MB are supplied to theinternal control circuit 113 of the IO chip 211. Here, the controlsignal MB is a bank mode signal indicating whether or not a plurality ofDRAM chips 201a, 201b in the memory module are formed in the 2-bankconstitution, and the control signal MIO is a signal for selecting theIO chip 211a, 211b.

An internal control circuit 113a receives the control signal MIO, MB tooperate, and controls the address control circuit, bank selection signalcontrol circuit 117. The shown internal control circuit 113a is similarto the internal control circuit 113 shown in FIG. 3 in that the controlsignal and latch signal LAT are produced. The address control circuit,bank selection signal control circuit 117 produces a bank selectionsignal BSELT/N as described later.

The IO chip 211 shown in FIG. 22 will be concretely described withreference to FIG. 23. The address data control circuit 117a whichreceives the system bank address signals BA0 to BA3 to operateindividually outputs internal bank selection signals (BA0T/NP toBA3T/NP) to the bank selection signal production circuit 117b.

On the other hand, the internal control circuit 113 receives a bank modeMB to output an internal bank mode signal MBS which sets the bankconstitution of the DRAM chip 210, and further outputs a control signalMIOS which sets the constitutions of the IO chips 211a, 211b. It is tobe noted that the internal bank mode signal MBS is a signal whichdetermines whether or not the DRAM inside is formed in the 2-bankconstitution. This means that the shown memory module can be selectivelyoperated in two banks or in a single bank.

The bank selection signal production circuit 117b shown in FIG. 23logically calculates the internal bank selection signals (BA0T/NP toBA3T/NP) and the signals on the laminate number recognition line (C4R,C8R) to output the bank selection signals (BA0T/N to BA2T/N) forselecting the bank on the IO chip 211a or 211b. On the other hand, thebank constitution selection signals BSELT, BSELN which designate thebank constitutions in the respective DRAM chips 201a, 201b.

Referring to FIG. 24, the respective DRAM chips 201 (affixed charactersare omitted) stacked on the IO chips 211a, 211b shown in FIG. 23 have amemory cell array 1 (bank A) and a memory cell array 2 (bank B), andthese banks A, B selectively operate in a single bank or 2-bankconstitution in response to the internal bank mode signal MBS.

Specifically, the DRAM chip 201 shown in FIG. 24 includes the DRAM chipselection circuit block 150 comprising the counter circuit 300, andfurther includes the control circuit 171, address buffer 172, databuffer 173, test circuit 176, and pad for test 176. Here, since the DRAMchip selection circuit block 150 and test circuit 176 are describedalready in the above-described embodiment, the description thereof isomitted here.

The shown control circuit 171 receives the internal bank mode signal MBSand control signal MIOS to output control signals 1 and 2 to the memorycell arrays 1 and 2 in response to MBS and MIOS. Furthermore, bank levelselection signals BSELT, BSELN which designate the bank levels in therespective DRAM chips 201a, 201b are supplied to the address buffer 172.The address buffer 172 outputs a column address signal to the memorycell arrays 1 and 2 in accordance with BSELT, BSELN, and further outputsrow address signals 1, 2 to the memory cell arrays A, B.

As apparent from this, the control circuit 171, address buffer 172, anddata buffer 173 shown in FIG. 24 operate as an array control circuitwhich controls the memory array.

Since an operation other than this operation is similar to theabove-described embodiment, the description is omitted.

In the IO chip 211 shown in FIG. 23, the internal control circuit 113produces the bank mode signal MBS in response to the bank mode signal MBof the system.

FIG. 25 shows another example of the IO chip 211. DRAM chip laminatenumber identification signals MC8 and MC4 are supplied to the internalcontrol circuit 113 of the shown IO chip 211 from the BGA terminal onthe interposer substrate. This internal control circuit 113 refers tonot only the bank mode signal MB of the system but also the leveldesignated by MC8 and MC4 to produce the bank mode signal MBS.

In the above-described embodiment, it is controlled by the signalsupplied to a BGA terminal MB whether or not to form the inside of theDRAM in the 2-bank constitution. Therefore, the internal bankconstitution can be varied in accordance with a system master's request.A fixed potential may be supplied to the MB terminal by the system, orthe terminal may also be switched in the same manner as in the systemcommand signal.

As described above, when the 2-bank constitution is formed in the DRAMchip, a minimum DRAM capacity can be handled even with a DRAM laminatenumber of two. Furthermore, the constitutions of four layers, eightlayers may be formed by the same IO chip and DRAM chip, various memorycapacity requirements can be handled, and productivity is enhanced.

An effect by the increase of the bank number will be described. A methodof using the memory bank differs with the system. However, when a pagehit ratio is high, a request from the system is waited for in a bankactivated state, and therefore a longer page length is effective inenhancing the hit ratio. When the page hit ratio is low, the requestfrom the system is waited for in a bank closed state, and therefore alarger bank number is more preferable.

Here, information such as a memory capacity, bank constitution, andassured operation speed of the module are written in the memory moduleat a manufacturing time, and the SPD chip is sometimes mounted having afunction to which the chip set refers in automatically setting thecontrol conditions at the system boot time. The present invention issimilarly applicable even to the memory module comprising the SPD chip.

Referring to FIG. 26, the memory module according to the fourthembodiment of the present invention is disposed. For the shown memorymodule, an IO substrate, that is, the IO chip 211 is mounted on theinterposer substrate 210, and the DRAM chips 201 formed of eight layersare stacked on the IO chip 211. Furthermore, an SPD chip 400 is mountedon the DRAM chip 201 in the uppermost layer. The SPD chip 400 is a ROMin which the memory capacity and the like are written as describedabove, the control conditions of the SPD chip 400 are read from the chipset at the system boot time, and the conditions are automatically set inthe system.

The SPD chip 400 is connected to the IO chip 211 by the throughelectrode 215 in the same manner as in the DRAM chip 201, and furtherconnected to the interposer substrate 210 via the pad on the IO chip211.

The operation of the shown memory module is similar to that of thememory module according to the second embodiment except the operation atthe boot time.

Referring to FIG. 27, another example in which the SPD chip 400 is usedis shown. Here, two IO chips 211a and 211b are mounted on the interposersubstrate 210. Eight DRAM chips 201a, 201b are stacked on each of the IOchips 211a and 211b. Furthermore, in the shown example, the SPD chip 400is attached only to the DRAM chip 201a on the IO chip 211a. The SPD chip400 is connected to the IO chip 211a via the through electrodes 215.

In this constitution, the SPD signal can be read by the IO chip 201a viathe through electrodes 215.

The chip set reads the information written in the SPD chip 400 at thesystem boot time. The information is taken into the IO chips 211a, 211bto produce the control signals of the DRAM chips 201a, 201b (MBS; bankconstitution in the DRAM chip, MIOS; IO constitution of the DRAM chip).

When the IO chips 201a, 201b read/access the SPD chip 400 in this mannerat an initialization setting time of the memory module, set informationsuch as internal timing setting and module constitution written in theSPD chip 400 at a manufacturing time may also be read to set theinternal circuit.

Moreover, as shown in FIG. 27, when two IO chips 211a and 201b aremounted, the SPD chip 4100 is mounted only on the DRAM chip 201a on oneside, connected to the pad on the IO chip 211a via the throughelectrodes 215, and further connected to the pad of the other IO chip211b by a wiring on the interposer substrate 210. Accordingly, thesignals from the SPD chip 400 can be read by both the IO chips 211a,211b.

Referring to FIG. 28, a laminate structure of the memory module shown inFIG. 27 is shown. As apparent from the drawing, the SPD chip 400 isdisposed only on the left DRAM chip 201a, and is not disposed on theright DRAM chip 201b. Furthermore, each of the shown DRAM chips 201a,201b has the 2-bank constitution, and two bank levels are applied to therespective DRAM chips 201a, 201b in this relation.

The system address, command, and clock signals are applied to two IOchips 211a, 211b in common, and the SPD chip 400 is accessed at thesystem boot time. When the SPD chip 400 is accessed, the SPD signals(SCL, SDA, SA0 to SA2) are output to the IO chips 211a, 211b and chipset.

FIG. 29 shows a connection relation of the IO chip 211a, DRAM chip 201a,and SPD chip 400 shown in FIG. 28, and FIG. 30 shows a connectionrelation of the IO chip 211b and DRAM chip 201b. The shown IO chip 211acomprises an SPD code decipher circuit 500 connected to the SPD chip400, and the SPD code decipher circuit 500 deciphers the SPD signal tooutput a decipher result to the internal control circuit 113. Theinternal control circuit 113 supplies an IO inner adjustment signal tothe input/output circuit 111 and input circuit 112 in accordance withthe decipher result to perform initial setting. Moreover, the controlsignals MBS and MIOS are supplied to the DRAM chip 201a on the IO chip211a to initially set each DRAM chip 201a.

The SPD signal is also supplied to the SPD code decipher circuit 500 ofthe IO chip 211b shown in FIG. 30 via the IO chip 201a, and the decipherresult is supplied to the internal control circuit 113 in the IO chip211b to perform the initial setting of the DRAM chip 201b in the samemanner as in the DRAM chip 201a on the IO chip 211a.

The operation of the memory module according to the present inventionwill be described with reference to FIG. 31. It is to be noted that theoperation of the memory module is basically similar in all theembodiments. On receiving the system command signals (ACT, RED, PRE)from the chip set, the IO chip 211 transmits the latch signal LAT,address signals IA0 to IAi, bank selection signals BA0 to 2T/N, commandsignal, and internal data signal (×256) to the DRAM chip 201.

In the shown example, 400 MHz is supplied as the system clock signal,system commands (ACT, RED, PRE) are supplied in synchronization with thesystem clock signal, and the latch signal LAT and in-DRAM latch signalare output after a predetermined timing in response to the systemcommands ACT, RED. As apparent from the drawing, the latch signal LATand the latch signal in the DRAM are produced at the same time interval.

The DRAM chip 201 receives the address, command, data signals by thelatch signal LAT transmitted from the IO chip 211 to start an internaloperation. Here, since the command signal is transmitted to the DRAMchip 201 by the latch signal LAT in synchronization with the systemclock, the timing between the command signals in the memory module isthe same as the time interval on the system.

As shown, when the system command ACT is supplied together with anaddress signal ADD, the corresponding DRAM chip is activated. When theread command RED is supplied in this state, internal data of 256 bitsare read as the system data four times by a unit of 64 bits.

Referring to FIG. 32, an operation is shown in a case where the readcommand RED is continuously supplied as the system command together witha system address Add, and even in this case, the internal data of 256bits is continuously read out as system data by a unit of 64 bits in atRAS period.

On the other hand, FIG. 33 shows an operation in a case where a writecommand (WRT) is supplied after the system command ACT. In this case, inthe DRAM chip, the latch signal in the DRAM, command signal, andinternal address signal are produced in synchronization with the systemcommands ACT and WRT, and the system data signal is written as theinternal data signal of 256 bits by a unit of 64 bits in synchronizationwith the DRAM latch signal.

As described above, the pad for test 175 and test circuit 176 are builtin the DRAM chip 201 in the memory module according to the presentinvention.

Referring to FIG. 34, a write operation in a case where each DRAM chip201 is tested. In this case, the test command signals (ACT, RED, PRE)are supplied from the test pad 175 in synchronization with a testtrigger signal. On receiving the test command signal, the test circuit176 transmits the latch signal for test, test address, test command, andtest data signal to the address buffer 172, control circuit 171, anddata buffer 173. In the shown example, since a test pad number isreduced, the signal for test is input continuously to rising, falling ofthe trigger signal for test, and modulated in the test circuit 176 toproduce the test address, test command.

The test data signal is input from one pin, and internal ×256IO isdegenerated and tested. The DRAM chip 201 receives the address, command,and data signal by the latch signal for the test transmitted from thetest circuit 176 to start the internal operation.

Here, since the test command is formed in the internal operation signalby the latch signal for the test in synchronization with the testtrigger signal, the timing between the commands in the DRAM chip isequal to a timing interval of the test command.

FIG. 35 is a timing chart showing an operation in a case where the readoperation of each DRAM chip 201 is tested. At a read operation time,expected value data is input from test data input/output, and comparedwith internal read data, and a comparison result is latched.

A judgment result is output and reset in a comparison cycle shown inFIG. 36.

FIG. 36 shows the constitution of an in-DRAM chip signal latch circuitwhich latches the judgment result. The latch circuit shown in FIG. 37 isused during the test, and comprises a circuit section which latches thetest address, command, data signal by the latch signal for the test, andan output section which is used at a normal operation time and which iscommon to the circuit section for latching the address, command, datasignal by the latch signal in the DRAM. In this constitution, since anin-DRAM chip production timing interval of the signal to be latched inthe circuit section can be equal at a test time and at a mounting time,it is possible to remove a defect of the DRAM chip in a wafer state.

A memory system constituted using the memory module according to thepresent invention will be described with reference to FIG. 38. In theshown memory system, the memory module (shown by 400a to 400d) includingthe laminate of the DRAM chips 201 shown in FIG. 1 and the like ismounted on a mother board 401 together with a memory controller (chipset) 402.

In the shown example, the respective memory modules 400a to 400d aremounted in a plane on the mother board 401. In this relation, planemounting sockets 403 are disposed in mounted positions of the memorymodules 400a to 400d, and the memory modules 400a to 400d areelectrically connected to the pads of the plane mounting sockets 403 viathe BGA terminals of the interposer substrate 210.

In this case, the data signal, address command signal, clock signal, andcontrol signal are supplied to the BGA terminals of the interposersubstrates 210 disposed in the memory modules 400a to 400d. Thesesignals are supplied to the signal pads on the IO chips 211 of thememory modules 400a to 400d and further to the interface circuit. Sinceconnections in the respective memory modules 400a to 400d are remarkablyshort, only a branch occurs on the signal wiring to such an extent thatthe branch is electrically ignorable (@1.6 Gbps).

In the shown example, the wirings of the data signal, address commandsignal, and clock signal can be formed in physically the same wiringtopology. Therefore, a difference is not made in a signal reach time(i.e., skew) in the respective memory modules 400a to 400d (especiallyIO chip input pads).

In this constitution, since the bus width per channel can be equal to ormore than that of a DDRII module, there is an advantage that the numberof packages connected to the bus does not increase as in the RDRAM.

Next, a memory system shown in FIG. 39 has a constitution in which thememory modules 400a to 400d shown in FIG. 38 are mounted on a mountingsubstrate 410 via the plane mounting sockets 403 and the mountingsubstrate 410 is mounted on the mother board 401 via a slot andconnector (not shown). In this manner, the memory system of the presentinvention may also use a constitution in which the mounting substrate410 including the stacked and mounted memory modules 400a to 400d isvertically disposed on the mother board 401. Even in this constitutionshown in the drawing, the wirings of the data signal (DQ), addresscommand signal, and clock signal are formed substantially in physicallythe same wiring topology. Therefore, the skew in the respective memorymodules 400a to 400d (especially, the IO chip input pads) can besuppressed.

When write, read simulation is performed at 1.6 Gbps with reference tothe memory system including the mounting substrates 410 shown in FIG.39, mounted in two slots, it has been confirmed that a window sufficientfor an eye pattern is opened. Similarly, a sufficient window can beobtained even in four slots.

On the other hand, when similar simulation is performed with respect toRDRAM including 16 devices mounted in two slots, any sufficient windowis not obtained.

This is supposedly because a received waveform in a far-end device isinfluenced by a reflection signal by another device input LC in a casewhere 16 devices are connected to the bus.

In the above-described embodiments, only the DRAM chip has beendescribed, but the present invention is not limited to this, and isapplicable to a system in which the transfer rate and width of theexternal data signal are different from those of the internal datasignal in the module.

As described above, a DRAM memory module according to the presentinvention has a structure in which an interposer, an IO chip, a throughelectrode, and a plurality of DRAM chips are stacked. According to thisstructure, an input circuit of an address, command, clock signal ismounted only on the IO chip, and a current consumption of the inputcircuit of the address, command, clock signal, which has heretofore beenconsumed by each DRAM chip on a conventional memory module, is only forone set on the IO chip. Similarly, a DLL, which has heretofore beenmounted on each DRAM chip, is mounted only on the IO chip in the memorymodule of the present invention, and the current consumption is only forone set. In the structure of the present invention, a wiring on a modulesubstrate corresponds to a through electrode, a size of the throughelectrode is only 450 μm even with eight laminates of about 50 μm, andcharge/discharge of the wiring is remarkably small. Therefore, in thepresent invention, a wiring charge/discharge current on the substrate inthe conventional module can largely be reduced.

In the memory module according to the present invention, only one DRAMchip in the module is accessed in response to an access command from amemory controller. Redundant operations of a control circuit section andcontrol signal on the DRAM chip in a case where all the DRAM chips or ½of the DRAM chips on the module are accessed as in a conventional DDRmodule can be eliminated to reduce the operation current of the wholemodule.

Furthermore, in the memory module according to the present invention, aregister or a PLL which has heretofore been mounted for timingadjustment with respect to a wiring delay on the module in systems suchas a conventional DDR is not required, and therefore the currentconsumption by these active components is reduced.

Moreover, since termination of the data signal wiring (DQ) in the DRAMchip required in a DDRII system is not required, a DC chip consumed herecan be reduced.

In the memory module of the present invention, only one DRAM chip in themodule is accessed with respect to one access command from the memorycontroller for reducing the operation current.

Moreover, for the DRAM chips to be stacked, it is preferable that allpatterns including the through electrodes be common in consideration ofproductivity. When all the patterns are common in this manner, a problemoccurs that it is difficult to individually transmit signals to the DRAMchips from the IO chip and to operate the chips. However, this problemcan be solved by a counter circuit disposed so as to produce a collationsignal for receiving signals by collation with a control signal or anaddress signal transmitted to each DRAM chip from the IO chip. A wiringfor this counter circuit is laid on a wafer on which the patterns of theDRAM chips have been formed after forming the through electrode.

What is claimed is:
 1. A method comprising: performing a first transferof first data, the first transfer being performed via through electrodesextending through a plurality of memory chips stacked on a control IOchip and connecting electrically between the control IO chip and each ofthe memory chips; and performing a second transfer of second data, thesecond transfer being performed via data lines connecting electricallybetween a controller and the control IO chip, and a bus width of thethrough electrodes being broader than that of the data lines.
 2. Themethod as claimed in claim 1, wherein the first transfer of the firstdata is performed in parallel via through electrodes between the controlIO chip and each of the memory chips and the second transfer of thesecond data is performed in serial via data lines between the controllerand the control IO chip.
 3. The method as claimed in claim 1, whereinthe bus width of the through electrodes is 2n (n denotes a naturalnumber of 1 or more) times of that of the data lines.
 4. The method asclaimed in claim 1, further comprising: generating the first data from aplurality of the second data, the first data comprising a first numberof bits, each of the second data comprising a second number of bits, andthe first number of the first data being larger than the second numberof the second data.
 5. The method as claimed in claim 4, wherein a sumof total bits configuring the plurality of the second data is equal tothe first number of the first data.
 6. The method as claimed in claim 1,further comprising: generating a plurality of the second data from thefirst data, the first data comprising a first number of bits, each ofthe second data comprising a second number of bits, and the first numberof the first data being larger than the second number of the seconddata.
 7. The method as claimed in claim 6, wherein a sum of total bitsconfiguring the plurality of the second data is equal to the firstnumber of the first data.
 8. A method comprising: supplying a pluralityof external data to data terminals of a control IO chip in serial toeach other; making up internal data in response to the supplied externaldata, the internal data comprising a first number of bits, each of thesupplied external data comprising a second number of bits, and the firstnumber being larger than the second number; and writing bits of themade-up internal data into selected one among a plurality of memorychips in parallel to each other, the memory chips being stacked on thecontrol IO chip, the writing being performed via thorough electrodesextending through the memory chips and connecting electrically betweenthe control IO chip and each of the memory chips.
 9. The method asclaimed in claim 8, wherein the first number is 2n (n denotes a naturalnumber of 1 or more) times of the second number.
 10. The method asclaimed in claim 8, wherein a sum of total bits configuring theplurality of the second data is equal to the first number of the firstdata.
 11. The method as claimed in claim 8, wherein the throughelectrodes has a broader bus width than the data terminals of thecontrol IO chip.
 12. The method as claimed in claim 8, furthercomprising; supplying address information to address terminals of acontrol IO chip, the address information being transferred via thethrough electrodes that is different from one that transfer the internaldata; and selecting, in response to a content of the supplied addressinformation, the selected one among the memory chips.
 13. A methodcomprising: reading out bits of internal data from selected one among aplurality of memory chips in parallel to each other, the memory chipsbeing stacked on a control IO chip, the read being performed viathorough electrodes extending through the memory chips and connectingelectrically between the control IO chip and each of the memory chips,making up a plurality of external data in response to the read-outinternal data, the internal data comprising a first number of the bits,each of the external data comprising a second number of bits, and thefirst number being larger than the second number; and sending bits ofthe made-up external data via data terminals of the IO chip to externalin serial to each other.
 14. The method as claimed in claim 13, whereinthe first number is 2n (n denotes a natural number of 1 or more) timesof the second number.
 15. The method as claimed in claim 13, wherein asum of total bits configuring the plurality of the second data is equalto the first number of the first data.
 16. The method as claimed inclaim 13, wherein the through electrodes has a broader bus width thanthe data terminals of the control IO chip.
 17. The method as claimed inclaim 13, further comprising: supplying address information to a controlIO chip, the address information being transferred via the throughelectrodes that is different from one that transfer the internal data;and selecting, in response to a content of the supplied addressinformation, selected one among the memory chips.
 18. A methodcomprising: making an access to a semiconductor device that comprises afirst semiconductor chip and a second semiconductor chip, the secondsemiconductor chip being stacked over the first semiconductor chip;accepting the access at the first semiconductor chip to perform a datatransfer between the first semiconductor chip and an outside of thesemiconductor device in a unit of a first number of bits; andperforming, in response to the accepting, a data transfer between thefirst and second semiconductor chips in a unit of a second number ofbits, the second number being greater than the first number.
 19. Themethod as claimed in claim 18, wherein the semiconductor device furthercomprising a third semiconductor chip stacked over the secondsemiconductor chip, and the performing is carried out between the firstsemiconductor chip and at least one of the second and thirdsemiconductor chips.
 20. The method as claimed in claim 19, wherein thesecond semiconductor chip including a plurality of first throughelectrodes each penetrating the second semiconductor chip and the thirdsemiconductor chip including a plurality of second through electrodeseach penetrating the third semiconductor chip, each of the first throughelectrodes being connected to an associated one of the second throughelectrodes, the data transfer between the first semiconductor chip andthe at least one of the second and third semiconductor chips beingperformed through at least one of the first and second throughelectrodes.
 21. The method as claimed in claim 20, wherein a bus widthof the first through electrodes is equal to that of second throughelectrodes.
 22. The method as claimed in claim 19, further comprising:selecting one of the second and the third semiconductor chip to carryout the performing between the first semiconductor chip and the one ofthe second and third semiconductor chips, and carrying out theperforming between the first semiconductor chip and the selected one ofthe second and third semiconductor chips in parallel to each other. 23.A memory module comprising: a plurality of stacked memory chips; aserial presence detect chip stacked with the plurality of memory chips,wherein the serial presence detect chip is stacked over the plurality ofstacked memory chips; and a plurality of through electrodes connectingeach of the plurality of stacked memory chips and the serial presencedetect chip.
 24. The memory module of claim 23 further comprising an IOchip stacked with the plurality of stacked memory chips and the serialpresence detect chip and connected to the plurality of throughelectrodes.
 25. The memory module of claim 24 wherein the plurality ofstacked memory chips are stacked over the IO chip.
 26. The memory moduleof claim 23 wherein the serial presence detect chip determines anoperation condition of the plurality of stacked memory chips.
 27. Thememory module of claim 23 wherein the serial presence detect chipcomprises memory.
 28. The memory module of claim 27 wherein the serialpresence detect chip comprises ROM.
 29. The memory module of claim 23wherein the serial presence detect chip comprises an indication of aselected one of memory capacity, bank constitution, and assuredoperation speed information for the plurality of stacked memory chips.30. The memory module of claim 23 wherein the serial presence detectchip provides information to set control conditions at system boot time.